Unquotes can't precede parens and they should be allowed to.

[baroquebobcat]

without this you can't do things like

def macro foo clazz
  quote { `clazz`(nil) }
end

references mirah/mirah#169

[ribrdb]

I remember specifically deciding not to handle this, but I can't remember if that was because it was hard to parse, hard for type inference, or something else. It's definitely awkward and worth revisiting though.